That Johnny Manziel might run too much for his own good in the NFL is the longest-standing red flag, along with his size, about the former Heisman Trophy winner's pro potential as a quarterback. That Manziel tucked and ran despite having open receivers at Texas A&M, however, raises that flag a bit higher.

But that's what NFL Media analyst and former Texans and Redskins personnel executive Charley Casserly told "NFL AM" he sees in watching film of the former Aggies star who could be the No. 1 overall pick to the quarterback-needy Houston Texans.

"Pocket discipline. When you watch tape on this guy, there are times I'm not sure what this guy sees. You've got guys wide open and, boom, he takes off and runs," Casserly said. "He may be a victim of his (own) ability to make plays running the football, so he doesn't stay in the pocket. I'd want to watch tape with him, what are you seeing, why are you running when you don't have to run?"

Manziel did a better job of staying in the pocket as a sophomore in 2013 than he did in his Heisman Trophy season of 2012, rushing for roughly half the yardage in his second year as a college starter while showing more pocket patience. Casserly, however, wants to see more.

"Clearly the other thing, you've got to get a handle on this guy's maturity. When he goes to the big city, it's not going to be College Station any more," Casserly said.

In a candid look at the draft's other quarterback prospects, Casserly had the following thoughts about Central Florida's Blake Bortles, Louisville's Teddy Bridgewater, and Alabama's AJ McCarron:

On Bortles: "This guy might be No. 1 when it is all said and done because he's a big strong-armed guy. When you watch the tape, in every single game I watched, he'll make some throws you can't explain, as far as making bad decisions. ... (Also) you'd like him to be a little more consistent on the accuracy to be the top pick."

On Bridgewater: "Everybody talks about (Bridgewater's) body build, being a lean guy, they worry about his durability. What is his strength and size potential? (That's) something we want to look at. The other thing is vocal leadership. You want to get a good handle on that at the combine and in the spring."

On McCarron: "Very productive quarterback, smart guy, but what I want to see (is) arm strength. I want to see this arm live. I just want to see at what level it's not strong. ... Is this guy Andy Dalton? I'm trying to make a positive out of that, but Dalton has his deficiencies, and one of them is accuracy, deep especially. Is he Andy Dalton, or is he a lesser Andy Dalton? That's my question on him."